【摘要】 本文研究CF_4-nCl₁改性HZSM-5分子筛催化剂的总酸量、酸强度及种类分布和催化性能的变化。结果表明,经CF_4-nCl_n改性后HZSM-5总酸量减少、酸性减弱;改性剂消除酸中心的能力为CF₃Cl>CF₂Cl₂>CFCl₃,CCl₄。F消除酸中心的能力大于Cl。HZSM-5中引入少量的F可增加B酸中心比例,而含F较高的催化剂B酸比例减少;Cl能使B酸比例减少。因此,通过CF_4-nCl_n对HZSM-5改性可以调变其酸性。弱酸中心有利于乙苯-乙醇烷基化,较强的酸中心则有利于乙苯脱烷基,深度改性的HZSM-5可明显改善对乙苯-乙醇烷基化的稳定性。更多还原

【Abstract】 It was found by using ammonia adsorption and TPD determination as well as infrared spectraof pyridine adsorbed that both the acidity and acid sites on the zeolite HZSM-5 modi-fied with CF_4-nCl_n were reduced, and the ratio of Lewis acid sites to Bronsted acid sites was also changed. The order of magnitude of these modifiers to make the zeolite losing acid sites is : CF₃Cl>CF₂Cl₂>CFCl₃ and CCl₄. There was more Bronsted sites on the modified catalysts containing small amount of F than that on the original HZSM-5, but it decreased sharply following the increase of F content. The stability for ethylbenzene alkylation with ethanol was improved and the activity for the dealky lation of ethylbenzene was suppressed" on the catalysts highly modified by CF₃Cl or CF₂Cl₂. These results suggest that weak acid sites may favor the alkylation of ethylbenzene with ethanol while strong acid sites favor the dealkylation of ethylhenzene.更多还原